Valve struck another nail in the coffin of Windows' monopoly over PC gaming, by releasing its smash-hit online multiplayer first-person shooter Team Fortress 2, on Steam for Linux. Its other online favorite, Counter Strike: Source is already available on the platform, which now boasts of 137 titles.

Team Fortress 2 follows the "free to play" model, the game is free to download and start playing. It uses an in-game currency to let players purchase high-quality equipment. All of the game's social features are enabled, the Source engine that drives it looks as visually complete on the OpenGL API as Windows' Direct3D.

With the introduction of Team Fortress 2, Valve is left with just a few more of its own developed games to port, including Counter Strike: Global Offensive, Portal franchise, the incomplete Half Life 2 trilogy, and Left 4 Dead 2. Here's hoping DOTA 2 comes ready for Linux from day one.